US4943280A - Self-seating flapper valve for an insufflation cannula assembly - Google Patents

Abstract

A cannula assembly for use in conjunction with insufflatory surgical techniques includes a cannula, a housing mounted on one end of the cannula, and a flapper valve mounted in the housing. The flapper valve includes a valve seat which is situated at an opening formed in the housing, a valve plug which is adapted to engage the valve seat to form a substantially gas tight seal with the valve seat, and a support plate on which the valve plug is mounted and which is biased to pivot the plug into and out of engagement with the valve seat. The valve plug is movable on the support plate so as to be self-aligning with the valve seat when the plug and valve are in engagement.

Description

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The present invention relates to an insufflation cannula assembly adapted to receive a trocar, endoscope or other surgical instrument and for use in conjunction with insufflatory surgical techniques, and more particularly relates to a valve used in the assembly for maintaining insufflation pressure in a body cavity.

2. Description Of The Prior Art

Insufflatory surgery involves filling a body cavity with a pressurized gas to maintain the cavity under a certain predetermined pressure. One way of performing the surgery is by first puncturing the skin in a desired body cavity region with a needle. The needle includes a stylet which introduces an insufflation gas into the body cavity to inflate it.

A trocar is then used to puncture the body cavity. The trocar is inserted through a cannula or sheath, which cannula partially enters the body cavity through the incision made by the trocar. The trocar may then be removed from the cannula, and an elongated endoscope may be inserted through the cannula to view the anatomical cavity.

Various types of cannula or trocar assemblies are provided with valves for maintaining a certain gas pressure in the cavity when the trocar or other surgical instrument is removed from the cannula.

For example, U.S. Pat. No. 4,654,030, which issued to Frederic Moll et al., and copending U.S. application Ser. No. 920,509, filed Oct. 17, 1986, disclose a trocar assembly having a cannula and employing a flapper valve to close off the cannula passage after the trocar or other instrument has been withdrawn.

As shown in FIG. 7 of the Moll et al. patent, the flapper valve includes aU-shaped flapper 82 and a grommet 77 formed with acentral opening 78 through which the trocar may be inserted or withdrawn. The flapper carries a circular pad 87, and is spring-biased so that the pad engages grommet 77 and forms a seal with the grommet.

Although the flapper valve disclosed in the Moll et al. patent works well in most applications to maintain pressure in the body cavity, there are certain inherent drawbacks in its design.

First, the circular pad is rigidly mounted on the flapper so that it cannot move with respect to the flapper. If the pad and grommet are slightly out of alignment when the valve closes, the pad may not seat properly on the grommet, and insufflating gas may leak from the body cavity through the valve.

Second, the circular pad is made of a deformable material such as Tygon (TM), and is formed by a molding process. Irregularities in the pad's grommet-engaging surface due to shrinkage of the pad material during its formation may provide leakage paths through the valve. Also, the pad bears with considerable spring pressure on the side of the trocar when the trocar is inserted into the cannula through the valve. A depression may form in the pad's surface which may cause further leakage when the valve closes.

Third, the circular pad is relatively flat or has a slight curvature. It engages protruding lips 88 formed on the grommet, which lips surround the grommet opening 78. With this structure, the flapper valve disclosed in the Moll et al. patent provides minimal contact area between the pad and the grommet, and any slight irregularity in one or the other may cause the valve to leak.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a valve for an insufflation cannula assembly which minimizes fluid leakage through the cannula.

It is another object of the present invention to provide a flapper valve whose sealing members automatically align with each other when the valve closes to provide an enhanced gas tight seal.

It is a further object of the present invention to provide a flapper valve whose sealing members contact each other over a greater surface area.

It is yet another object of the present invention to provide an insufflation cannula assembly for use with a trocar, endoscope or other surgical instrument, which cannula assembly provides negligible or no gas leakage.

It is a still further object of the present invention to provide a flapper valve which is an improvement over the flapper valve disclosed in Moll et al. U.S. Pat. No. 4,654,030.

In one form of the present invention, a cannula assembly for use in conjunction with insufflatory surgical techniques includes a cannula having opposite open ends, a housing mounted on one end of the cannula and having an opening formed in the housing, and a flapper valve mounted in the housing to seal the cannula passage when a surgical instrument, such as a trocar, endoscope or the like, is withdrawn from the cannula.

The flapper valve basically includes a valve seat situated at the housing opening, a valve plug which engages the valve seat and forms a substantially fluidtight seal with the seat, and a support plate and spring mechanism for mounting the valve plug in the housing and for pivoting the plug into and out of engagement with the valve seat.

The valve seat has an opening formed through its thickness, which opening is in communication with the cannula passage. The valve seat is positioned in the housing such that its opening is co-axial with the cannula so that a surgical instrument, such as a trocar or endoscope, may be inserted through the valve seat opening and into the cannula passage.

The valve plug is mounted loosely but securely on the support plate so that it can move radially on a surface of the support plate and align itself with the opening formed in the valve seat when the two engage each other. The surface of the valve plug which engages the valve seat has a frusto-conical shape so that the surface is partially received by the valve seat opening when the valve closes.

The support plate is basically a U-shaped member which extends from the radial side of an upstanding post mounted in the housing. A helical spring mounted co-axially on the post engages the housing and the support plate and biases the valve plug into engagement with the valve seat. A trocar or other surgical instrument inserted through the valve seat opening will cause the valve plug to pivot away from the valve seat and out of the trocar's axial path of travel between the valve seat opening and the cannula passage.

Preferred forms of the flapper valve and insufflation cannula assembly, as well as other embodiments, objects, features and advantages of this invention, will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the cannula assembly of the present invention with a trocar assembly mounted thereon.

FIG. 2 is a sectional view of the cannula assembly and trocar assembly shown in FIG. 1, taken alongline 2--2 of FIG. 1.

FIG. 3 is an exploded view of the cannula assembly of the present invention.

FIG. 4 is an isometric view of the cannula assembly shown in FIG. 3 with its housing partially broken away.

FIG. 5 is a rear perspective view of a portion of the cannula assembly.

FIG. 6 is a partial sectional view of the flapper valve used in the cannula assembly of the present invention.

FIG. 7 is a top view of the cannula assembly with its housing partially broken away.

FIG. 8 is an enlarged, detailed view of a portion of the flapper valve of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1 and 2 of the drawings, it will be seen that acannula assembly 2 used in connection with insufflatory surgical techniques basically includes acannula 4 and ahousing 6 mounted on one end of thecannula 4. Thecannula 4 is formed as an elongated sleeve having opposite proximate and distal open ends, and thus defines acannula passage 8 in its interior. Thecannula 4 may be formed from a stainless steel or other rigid material.

Thehousing 6 of the cannula assembly is rigidly secured to the proximate end of thecannula 4. It has an open interior for mounting other components of the cannula assembly, and has arear opening 10 defined by acircular flange 12 extending inwardly of the housing, which opening 10 is situated co-axially with thecannula 4. An 0-ring 13 (see FIG. 3) may be mounted on thecannula 4 to prevent leakage between the cannula and the housing. Additionally, thehousing 6 includes astopcock port 14 into which the nozzle of astopcock 16 is inserted (see FIG. 4), theport 14 being provided for passing additional insufflating gas into the body cavity.

Thecannula assembly 2, with itscannula 4 and itshousing 6, is adapted to receive a surgical instrument through the opening 10 in its housing. An example of such an instrument is thetrocar assembly 20 shown in FIGS. 1 and 2 of the drawings, the trocar assembly being mounted on the rear side of thehousing 6.

Thetrocar assembly 20 basically includes a hand grip portion orhead 22, anobturator 24 mounted on thehead 22 of the trocar assembly and extending outwardly from the head, and anobturator shield 26 which houses theobturator 24. Theobturator 24 is formed with a piercingtip 28 for puncturing the body cavity. Aspring 30 in thehead 22 of the trocar assembly biases theshield 26 axially away from the head so that it covers theobturator tip 28.

Thetrocar assembly 20 is mounted on thecannula assembly 2 so that itsobturator 24 andshield 26 are slidably received in thecannula passage 8 with the obturator shield extending beyond the distal end of thecannula 4.

In operation, the distal end of the cannula/trocar assembly is placed against the skin at the body cavity region, and pressure is exerted on the assembly against the skin. This pressure causes theobturator shield 26 to be pushed rearwardly against the force of thespring 30 to a retracted position, thereby exposing the piercingtip 28 of the obturator. The tip enters the skin and underlying tissue with continued pressure. Once the tip has penetrated the tissue and has entered the cavity, the force against the distal end of theshield 26 ceases and the shield is automatically moved axially forward to its extended position covering thetip 28 through the action of thespring 30.

A more detailed description of the trocar assembly described herein, and its operation, is provided in Moll et al. U.S. Pat. No. 4,654,030, which is incorporated herein by reference.

As is provided in the device disclosed in the above-identified Moll et al. patent, thecannula assembly 2 of the present invention includes a flapper valve which opens to allow a surgical instrument, such as thetrocar assembly 20, to be inserted through thecannula 4, and closes when the surgical instrument has been withdrawn, in order to maintain gas pressure in the body cavity which has been inflated with an insufflation gas. The flapper valve of the present invention as shown in FIG. 3 basically includes three components: avalve seat 32, avalve plug 34 which engages thevalve seat 32, and amechanism 36 for mounting thevalve plug 34 and for pivoting the plug into and out of engagement with thevalve seat 32.

As shown in FIGS. 3 through 8 of the drawings, thevalve seat 32 is mounted in thecircular flange 12 at therear opening 10 formed in thehousing 6 of the cannula assembly. Theseat 32 basically includes aforward portion 38 and arearward portion 40 which are interconnected and which define arecess 42 between them, whichrecess 42 receives thecircular flange 12 of the housing. Therearward portion 40 is preferably circular, and is received in arecess 44 formed in thecircular flange 12.

Theforward portion 38 is substantially rectangular, and has a greater transverse width than the diameter of the circularrearward portion 40 so that it extends substantially to the oppositelateral sides 46 of thehousing 6. The forward andrearward portions 38, 40 contact the sides of the flange over an area sufficient to prevent leakage.

Thevalve seat 32 includes anopening 48 formed centrally through its thickness. Thevalve seat 32 is situated in thehousing 6 so that itsopening 48 is co-axial with thecannula 4 and is in communication with thecannula passage 8 through the interior of the housing; this will allow a surgical instrument, such as thetrocar assembly 20 shown in FIGS. 1 and 2, or an endoscope, for example, to pass through thevalve seat opening 48 and into thecannula passage 8 from the rear side of thecannula assembly housing 6.

A portion of thevalve seat 32 surrounding the opening is reduced in thickness. This portion is defined by acircular recess 50 formed in therearward portion 40 of the valve seat, and a recessedgroove 52 formed in the surface of theforward portion 38 of the valve seat and concentrically surrounding theopening 48.

Thevalve seat 32 is formed from a rubber or other elastic material. As will be seen, because of the elasticity of the material from which it is formed and the reduced thickness of the area surrounding theopening 48, thevalve seat 32 will deform to accommodate thevalve plug 34 and thereby conform to the shape of thevalve plug 34 when the two engage each other, with substantial areas of the two being in contact so as to form a substantially gas tight seal. Also, the reduced thickness portion at 50 and 52 surrounding thevalve seat opening 48 allows thevalve seat 32 to expand and closely engage theobturator shield 26 of thetrocar assembly 20 or other surgical instrument inserted in the cannula assembly, and to prevent fluid from escaping from the body cavity.

As mentioned previously, the flapper valve also includes amechanism 36 for mounting thevalve plug 34 and for pivoting the valve plug into and out of engagement with thevalve seat 32. As shown in FIG. 3 of the drawings, such a mechanism includes asupport plate 54 which is preferably U-shaped. Thesupport plate 54 extends outwardly from a radial side of anupstanding post 56 mounted in thehousing 6 of the cannula assembly.

A tensionedhelical spring 58 is co-axially mounted on thepost 56, and includes two ends 60, 62. Oneend 60 bears against aside 46 of thecannula housing 6, and theother end 62 bears against therear side 63 of the support plate below atab 64 extending outwardly from the rear side, whichtab 64 keeps the spring end in place. Thespring 58 biases thesupport plate 54 such that thevalve plug 34 mounted on the plate will engage thevalve seat 32 to effect a gas tight seal.

When a trocar or other surgical instrument is inserted through thevalve seat opening 48 into thehousing 6 of the cannula assembly, it will engage thevalve plug 34 and cause thesupport plate 54 to pivot against the force of thespring 58 towards theside 46 of the housing so that thevalve plug 34 is out of engagement with thevalve seat 32. This opens the valve and allows the surgical instrument to be inserted through the interior of thecannula assembly housing 6 and into thecannula 4. When the trocar or surgical instrument is withdrawn, thesupport plate 54 is spring biased to pivot so that thevalve plug 34 will automatically engage thevalve seat 32, thereby closing the valve.

Alever 66 is provided on the outside of thehousing 6. Thelever 66 is mounted to theupstanding post 56 and pivots with the post. Thelever 66 is provided for the surgeon to manipulate so that the valve can be manually opened to desufflate the body cavity. To ensure fluidtightness, an 0-ring 68 is mounted on the post between thespring 58 and thelever 66.

Thesupport plate 54 also has anopening 70 formed through its thickness, that is, between its rear andfront sides 63, 65. As will be seen, theopening 70 is provided for mounting thevalve plug 34 to the support plate.

As seen in FIG. 8, thevalve plug 34 of the flapper valve basically includes afront face 72 and arear face 74 opposite the front face. Aportion 76 of the front face is formed with a conical shape, and more preferably, a frusto-conical shape. The conically-shapedportion 76 of the valve plug is preferably sloped inwardly on its sides at an angle A of about 30°.

Thefront face 72 of the valve plug is also formed with aflange 78 which surrounds the conically-shapedportion 76.Flange 78 acts to ensure that the tip ofshield 26 of the trocar assembly, or other surgical instrument which may be inserted, is guided into thecannula 4 and does not momentarily get hung up at the joint formed byvalve plug 34 andsupport plate 54.

As mentioned previously, thevalve plug 34 is mounted on thesupport plate 54 and pivots with the support plate into and out of engagement with thevalve seat 32. One of the important features of the flapper valve of the present invention which distinguishes it from the valve employed in the trocar disclosed in U.S. Pat. No. 4,654,030 (Moll et al.) is that thevalve plug 34 is loosely but securely mounted on thesupport plate 54 so that it can move radially to a certain extent on the front face of the support plate. The ability of theplug 34 to move with respect to thesupport plate 54 and the particular shape of the valve plug (i.e., conical or frusto-conical) provide the valve plug with a self-seating capability which allows it to automatically align itself with thevalve seat 32 when the two engage.

Astem portion 80 extends outwardly from therear face 74 of thevalve plug 34. As will be seen, thestem portion 80 is provided for mounting thevalve plug 34 to thesupport plate 54, and for providing the valve plug with a degree of radial movement on the front side of the support plate.

Thestem portion 80 may include a free end on which is mounted a retaininghead 82. Additionally, the retaininghead 82 may form the free end of thestem portion 80. The retaininghead 82 in its preferred form is also frusto-conically shaped with sides that converge in a direction away from therear side 63 of the support plate, preferably sloping inwardly at an angle B of about 20°.

Thevalve plug 34 is mounted on thesupport plate 54 with its conically-shapedfront face 72 and its retaininghead 82 disposed on opposite front andrear sides 65, 63 of the support plate, respectively, and with itsstem portion 80 received by thesupport plate opening 70.

The retaininghead 82 is made oversized, that is, with a diameter that is greater than that of the support plate opening 70, to securely connect thevalve plug 34 to thesupport plate 54. However, thestem portion 80 of the valve plug is formed with a diameter that is less than that of thesupport plate opening 70. Thus, when mounted on thesupport plate 54, thevalve plug 34 is free to move in any radial direction on thefront side 65 of the support plate, and is limited in its radial movement by the difference between the diameters of the support plate opening 70 and thestem portion 80.

For example, if the support plate opening 70 is formed with a diameter of 0.127 inches and the valve plug stemportion 80 is formed with a diameter of 0.095 inches, then the valve plug will be able to travel 0.016 inches from the center of the support plate opening in any radial direction.

Thevalve plug 34 is thus free to "float" on the surface of thesupport plate 54 in any radial direction, and to align itself with thecentral opening 48 formed in thevalve seat 32. When the valve closes, the engagement of thevalve seat 32 with the frusto-conical front face of thevalve plug 34 forces the valve plug into proper alignment with the valve seat to effect a gas tight seal.

Therear face 74 of thevalve plug 34 is also formed with a recessedportion 84 concentrically surrounding thestem portion 80. This recessedportion 84 is provided basically for two reasons. First, it provides the plug with less surface area on its rear face 73 to contact thefront side 65 of the support plate. This reduces the drag or friction between the two and allows free movement of thevalve plug 34 on thesupport plate 54.

Second, if desired, the recessedportion 84 may serve to receive a silicone grease or other lubricant to lubricate the interface between the valve plug and the support plate, which also minimizes friction between the two.

If desired, thefront face 72 of thevalve plug 34 may be formed from an inelastic material such as plastic, aluminum, stainless steel or the like. The retaininghead 82 may be formed from the same or other material as thefront face 72 of the valve plug and joined to the end ofstem portion 80 after the stem portion has been mounted in the support plate opening 70, or may be formed from an elastic material and force-fitted throughplate opening 70. The retaininghead 82, formed of elastic material, can compress and then expand after its insertion through the support plate opening, and thereby return to an intentional interference.

Thevalve seat 32, being molded of rubber or other elastic material, conforms by stretching and compressing to the shape of thevalve plug 34 when the valve plug is wedged in thevalve seat opening 48. Thus, the valve seat surrounding theopening 48 can engage thevalve plug 34 over substantially all of its entire thickness to form an effective gas tight seal.

Thevalve plug 34 may be mounted in a circular recess 86 (see FIG. 8) formed in thefront side 65 of thesupport plate 54, the diameter of thecircular recess 86 being made sufficiently large so as not to limit the radial movement of the valve plug on the support plate.

The flapper valve of the present invention provides an enhanced gas tight seal by its capability of being self-seating. More specifically, the frusto-conical shape of thevalve plug 34 and its ability to "float" on thesupport plate 54 allow it to come into proper alignment with thevalve seat 32 when the two engage. Furthermore, the configuration and elasticity of thevalve seat 32 and the particular shape of thevalve plug 34 permit the two to contact each other over a greater surface area, thus ensuring an effective seal.

Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.

Claims (12)

We claim:

1. A flapper valve for an insufflation cannula assembly, the cannula assembly including a cannula defining a cannula passage and a housing mounted on one end of the cannula and having an opening formed therein, the flapper valve being mounted in the housing of the assembly, the flapper valve comprising:

a valve seat formed of a resilient material and situated at the housing opening, said valve seat having an opening formed therein, said valve seat opening being in communication with the cannula passage and being adapted to allow a surgical instrument to pass therethrough and into the cannula passage, said valve seat having an annular portion of reduced thickness defining said opening, said annular portion thereby being of greater flexibility than adjacent portions thereof;

a valve plug having a conically or frusto-conically shaped front face which engages said valve seat, said valve plug being adapted to engage said valve seat at said opening thereof and to form a seal therewith;

biasing means for biasing said valve plug into engagement with said valve seat; and

means for mounting said valve plug in the housing and for pivoting said valve plug into and out of engagement with said annular portion of said valve seat, said valve plug being movable on said plug mounting means sufficient to provide said valve plug with self-seating capability to thereby allow said valve plug to automatically align itself with said valve seat opening when said valve plug and said valve seat are in engagement, whereby said self-seating capability of said valve plug combines with said resilient annular flexible portion of said valve seat to provide a substantially gas tight seal.

2. A flapper valve as defined by claim 1, wherein the valve plug includes said front face which engages the valve seat, and a rear face opposite said front face, and further includes a stem portion extending outwardly from the rear face thereof; and wherein the plug mounting means includes a support plate, the support plate having an opening formed therein, the opening being adapted to receive the stem portion of the valve plug to allow the plug to be mounted on a surface of the plate, the diameter of the support plate opening being greater than the diameter of the plug stem portion; and wherein the flapper valve further includes means for securing the stem portion within the support plate opening.

3. A flapper valve as defined by claim 2, wherein the stem portion of the valve plug includes a free end; and wherein the plug further includes a retaining head, the retaining head being mounted on the free end of the plug stem portion, the retaining head having a greater diameter than that of the support plate opening.

4. A flapper valve as defined by claim 1, wherein the valve plug includes said front face which engages the valve seat, and a rear face opposite said front face, and further includes a stem portion extending outwardly from the rear face thereof, the stem portion having a free end, and a retaining head mounted on the free end of the plug stem portion; and wherein the support plate has two opposite sides and has an opening formed through the thickness thereof, the opening receiving the valve plug stem portion so that the retaining head and front face are disposed on opposite sides of the support plate, the diameter of the support plate opening being greater than that of the stem portion and being less than that of the retaining head.

5. A flapper valve as defined by claim 1, wherein the front face of the valve plug is formed from a substantially inelastic material.

6. A flapper valve as defined in claim 1, wherein the valve seat is formed from an elastic material.

7. A flapper valve as defined by claim 1, wherein the valve plug includes a front face having a conically-shaped portion and a flange surrounding the conically-shaped portion, and further includes a rear face opposite the front face, the front face being adapted to engage the valve seat.

8. A flapper valve as defined by claim 7, wherein the rear face of the valve plug includes a recessed portion.

9. A flapper valve as defined by claim 1, wherein the plug mounting means includes a support plate, the support plate being pivotally mounted in the housing and having the valve plug mounted thereon, and being biased to pivot the valve plug into engagement with the valve seat.

10. A flapper valve as defined by claim 1, wherein the valve plug includes a stem portion extending from a surface thereof, the stem portion being loosely received in an opening formed in the plug mounting means.

11. A flapper valve as defined by claim 1, wherein the valve seat is situated in the housing such that the valve seat opening is co-axial with the cannula.

12. An insufflation cannula assembly, which comprises:

a cannula having opposite end portions;

a housing mounted on one end of the cannula, said housing having an opening formed therein; and

a flapper valve mounted in the housing, said flapper valve including a valve seat disposed at the housing opening and having an opening formed therein to allow a surgical instrument to pass therethrough and into the cannula, said valve seat formed of a resilient material and having an annular portion of reduced thickness defining said opening, said annular portion being of greater flexibility than adjacent portions thereof due to said reduced thickness, a valve plug adapted to engage said valve seat at the opening thereof and to form a seal with said valve seat, and means for mounting said valve plug and for pivoting said valve plug into and out of engagement with said valve seat, said valve plug being movable on said plug mounting means so as to provide said valve plug with self-seating capability to allow said valve plug to automatically align itself with said valve seat opening when said plug and said valve seat are in engagement, whereby said self-seating capability of said valve plug combines with said resilient annular flexible portion of said valve seat to provide a substantially gas tight seal.

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